Computational complexity of stereo video processing is important in rendering of three-dimensional (3D) graphics and, specifically, in visualization of 3D scenes in low-power (i.e., battery-powered) devices, such as mobile phones, mobile media players, Personal Digital Assistant (PDA) devices, and the like. Visualization of 3D scenes may be useful in presentation of some movies, video games, user interfaces, and other 3D graphics applications.
In general, the difficulties in rendering of 3D graphics on a stereo-enabled display (e.g., auto-stereoscopic or stereoscopic display) come from the efficiency and reality aspects of the stereo video processing. Limited computational resources of the low-power devices may cause rendering of 3D graphics to be an excessively time-consuming routine. Despite the considerable efforts devoted to increasing performance of stereo video processing, further improvements would be desirable.
Additionally, the ability to allow users to customize their viewing experiences would also be desirable. The Human Visual System (HVS) perceives depth when two views of the same scene are presented to the left eye and right eye, respectively. Planar 3D displays, either stereoscopic or auto-stereoscopic, rely on providing two different views to the left eye and right eye, respectively, that are consistent with what the eye would perceive when viewing the scene directly. Therefore, points located at different depths in the scene will be shifted differently in the two views. The shift in location is called disparity when it refers to the images or parallax when this location is on the screen.
The parallax for a given point is positive when the location of this point on the screen for the left view is to the left of the location of this point on the screen for the right view. If the location of this point on the screen for the left view is to the right of the location of this point on the screen for the right view, then, the parallax is negative. If the location for both views is the same, the parallax is null. The location in space containing all the points that have zero parallax is known as the convergence plane. Negative parallax provides a pop-out effect whereas positive parallax provides a deep effect (as if seen through a hole or a window).
Given certain viewing conditions such as screen properties and viewing distance, there exists a maximum image disparity for which each individual is able to make their eyes converge. This is called the fusible range. The range of positive and negative disparities is not symmetric and depends on each individual. The perceived retinal disparity of the screen parallax depends on the image disparity, the pitch of the pixels on the screen (related to the size and resolution of the screen) and the viewing distance. Due to variation among in individuals' eyes as well as variances in viewing conditions, the effectiveness of parameters used for rendering optimal 3D content may vary for different viewers.